Here in Madrid, I have just been through the longest, hottest heatwave of my life. For more than a week, temperatures hovered near or at 40C. (For comparison: Britain’s all-time highest temperature is 38.7C.) At night we’d sleep with the fans on and windows open, choosing street noise over suffocation. The city became less productive and less fun: 10-minute journeys felt too long, the kids’ school closed in the afternoons and their football matches were cancelled. Vulnerable people died. Heatwaves in Spain now kill as many as 1,500 to 1,700 people every year.
Others fried with us. Heatwaves and drought hit much of western Europe and the US, where dozens of local weather stations registered record daily temperatures. In Nevada and Arizona, Lake Mead’s water levels sank to an all-time low, endangering drinking supplies for nearly 25 million Americans. It was the US’s worst heatwave since, well, May. The global rise in deaths from heat is projected to more than offset the fall in deaths from cold. With climate change making heatwaves ever more frequent, how will we cope? And which places won’t?
Rich countries have adapted gradually. In prewar New York summers, recalled the playwright Arthur Miller, families would sleep in their underwear on fire escapes or camp out in Central Park with their alarm clocks. Then came air-conditioning.
Europe began adapting after a 2003 heatwave killed more than 70,000 mostly elderly people, some of whom then decomposed alone and unnoticed in their homes. Countries started issuing public-health warnings, opening neighbourhood “cooling centres”, replacing concrete in cities with trees and checking in on older residents. Fewer Spaniards now die at a given level of heat. By luck and design, relatively cool Europe may find itself the most future-proofed continent, though that’s not saying much.
“The US is way behind,” says Eric Klinenberg, professor at New York University, who wrote Heat Wave about the disaster that killed 739 in his native Chicago in 1995. To adapt to climate change, air-conditioning isn’t enough. You also need a functioning society. Klinenberg says: “American infrastructure is not up to the challenge of a hotter, wetter world.”
As heatwaves get longer, the US will eventually suffer one that lasts weeks. When that happens, says Klinenberg, the country’s aged electrical grids may not cope with rising demand. If grids fail, food will rot, residents of high-storey apartment buildings risk being trapped without elevators, and it won’t be possible to pump water to people living above the sixth floor.
Most migration happens within a country rather than internationally, and Klinenberg predicts that Americans will increasingly move to cooler parts of the US. (Though some moves will be unpredictable; I know an elderly couple now living essentially homeless in southern California after wildfires destroyed their Colorado home.) The great American migration to the Sunbelt may go into reverse. Hot regions with falling house prices could become ghettos.
But the impact will be worst in hotter and poorer developing countries. Most people today live in the tropics and subtropics. We know the maximum heat at which human beings can survive, the so-called wet-bulb temperature of 35C, which is calculated depending on the local mix of heat and humidity. Currently, fewer than one million people live in areas that average 38-45C in the shade during the hottest month, estimates the International Organization for Migration (IOM). That number will reach 30 to 60 million by 2100, even if we limit average global temperature rises to 1.5C.
But we almost certainly won’t hold at 1.5C. Step one would be nearly halving carbon emissions by 2030, but in fact they have risen to their highest level ever. More probably, using the IOM’s projections, by 2100 several hundred million people will be stuck in unlivable places. Epicentres will be west Africa, the Gulf and south Asia, where India and Pakistan recently suffered their own record heatwave. Few climate victims will make it to richer countries, which will keep recruiting migrant software developers and nurses while barring the desperate poor with ever more high-tech border controls.
More people will die. We have seen in Darfur, Syria and Mali that drought can encourage violent competition between groups. Klinenberg is hoping for political and technological breakthroughs to transform our energy systems to supply renewables — now much cheaper than before. But he says: “This is the beginning of a reckoning. We’re living through the very first stages.”
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